Hydrophobic tooth whitening system and methods of use

ABSTRACT

A tooth whitening system comprising a dental tray having a surface operable to confront a tooth surface, and a tooth whitening composition comprising a whitening agent and a hydrophobic polymer carrier. The tooth whitening composition is preferably substantially non-water soluble. A tooth whitening kit is also provided using a dental tray and the tooth whitening composition comprising a whitening composition and a hydrophobic polymer carrier.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 10/754,065 filed on Jan. 7, 2004, which is acontinuation-in-part of U.S. patent application Ser. No. 10/642,458filed on Aug. 15, 2003.

The disclosures of the above applications are incorporated herein byreference.

INTRODUCTION

The present invention relates to tooth whitening systems employingcompositions comprising hydrophobic polymers. Embodiments of the presentinvention include tooth whitening systems having dental trays andemploying whitening compositions comprising a hydrophobic polymercarrier and a whitening agent.

There is a general desire for people to have white teeth. Such whiteteeth are an indication of a good health and in particular good oralcare health. A problem is that various foods and the use of tobacco willdiscolor teeth. Beverages such as coffee, tea and cola beverages candiscolor teeth.

As a result various products and procedures have been developed towhiten teeth. These products and procedures are either purchased and/orused directly by the consumer or are applied by a dentist or otherprofessional. The more effective products and procedures are those thatare performed by a dental professional.

Typically this consists of the dental professional forming a dental trayfrom an impression of a person's teeth. Custom dental trays can becreated by any of the procedures, well known in the art. After thedental tray is formed to the structure of the teeth a whiteningformulation is placed in the tray and the tray placed into the mouth andagainst the teeth to be treated. A dental tray having whiteningcomposition for in-home use is typically left in the mouth for fromabout 10 minutes to several hours; i.e., up to 12 or more hours. If thetreatment occurs in the dental office, the time of the treatmenttypically will be from about 0.5 hour to about 2 hours.

The products used solely by consumers primarily comprise whiteningstrips and brush-on products. Whitening strips are plastic strips withthe whitening formulation on one surface. The surface with the whiteningformulation is pressed against one's teeth and left in contact with theteeth for about 30 minutes. The plastic strip then is removed. Thebrush-on products are painted into teeth and the user keeps his/hermouth at least partially open for up to about a minute until theformulation dries onto the teeth. In both cases saliva will dilute andflush the tooth whitening composition from the user's teeth. This occursmore so with strips, since foreign materials (such as, a plastic strip),will enhance saliva flow in the mouth. These products are useful toremove some tooth staining. However, they are typically not asconcentrated, and thus not as effective tooth whitening systems, as aredental trays, and in particular the use of dental trays by dentalprofessionals.

A problem with the various whitening compositions that are used indental trays is that they are substantially soluble in water and saliva.This results in a dilution of the whitening formulation during use. Inorder to overcome this problem producers of these whitening formulationshave increased the concentration of the whitening actives. However, thiscauses a problem of increased tooth sensitivity, gum irritation and thepotential long term for lesions. Another solution disclosed in U.S. Pat.No. 5,846,058 has been to use higher viscosity tooth whiteningcompositions. This increases dilution time and flush time but is not afull solution to the problem. A better solution to this problem is touse a carrier and actives that are substantially insoluble in water andsaliva, the carrier being about fully insoluble in water and saliva. Theactive must have some solubility in order to attack and remove toothstains. However, it is preferred that the solubility of the active isrelatively low. In this way, tooth whitening compositions with a lowerconcentration of active can be used to enhance whitening through alonger contact time at a more sustained active concentration.

SUMMARY

The present invention provides tooth whitening systems. Embodimentsinclude a tooth whitening system comprising a dental tray having asurface operable to confront a tooth surface and a tooth whiteningcomposition comprising a whitening agent and a hydrophobic polymercarrier.

In another embodiment, the present invention further provides a methodof whitening a surface of a tooth, comprising contacting the surfacewith a whitening composition contained in a dental tray. The whiteningcomposition comprises a whitening agent and a hydrophobic polymercarrier.

Another embodiment includes a tooth whitening kit, for whitening thesurface of a tooth in the oral cavity of a human or other animalsubject, comprising (a) a dental tray operable for insertion into theoral cavity of the subject, comprising a reservoir. The kit alsocomprises (b) a tooth whitening composition comprising a peroxidewhitening agent and a hydrophobic siloxane polymer carrier having aviscosity of at least about 50,000 centipoise (cP).

It has been discovered that compositions and methods of this inventionafford advantages over whitening compositions among those known in theart including one or more of: enhanced whitening efficacy, providing ahigher available concentration of whitening agent, adherence of thewhitening composition to the tooth surface even in the presence ofsaliva and sustained and controlled delivery of the whitening agent fora longer duration of time Further uses, benefits and embodiments of thepresent invention are apparent from the description set forth herein.

DESCRIPTION

The following definitions and non-limiting guidelines must be consideredin reviewing the description of this invention set forth herein. Theheadings (such as “Introduction” and “Summary,”) and sub-headings (suchas “Whitening Compositions” and “Methods”, for example) used herein areintended only for general organization of topics within the disclosureof the invention, and are not intended to limit the disclosure of theinvention or any aspect thereof. In particular, subject matter disclosedin the “Introduction” may include aspects of technology within the scopeof the invention, and may not constitute a recitation of prior art.Subject matter disclosed in the “Summary” is not an exhaustive orcomplete disclosure of the entire scope of the invention or anyembodiments thereof. Classification or discussion of a material within asection of this specification as having a particular utility (e.g., asbeing an “active” or a “carrier” ingredient) is made for convenience,and no inference should be drawn that the material must necessarily orsolely function in accordance with its classification herein when it isused in any given composition.

The citation of references herein does not constitute an admission thatthose references are prior art or have any relevance to thepatentability of the invention disclosed herein. Any discussion of thecontent of references cited in the Introduction is intended merely toprovide a general summary of assertions made by the authors of thereferences, and does not constitute an admission as to the accuracy ofthe content of such references. All references cited in the Descriptionsection of this specification are hereby incorporated by reference intheir entirety.

The description and specific examples, while indicating embodiments ofthe invention, are intended for purposes of illustration only and arenot intended to limit the scope of the invention. Moreover, recitationof multiple embodiments having stated features is not intended toexclude other embodiments having additional features, or otherembodiments incorporating different combinations the stated of features.Specific Examples are provided for illustrative purposes of how to makeand use the compositions and methods of this invention and, unlessexplicitly stated otherwise, are not intended to be a representationthat given embodiments of this invention have, or have not, been made ortested.

As used herein, the words “preferred” and “preferably” refer toembodiments of the invention that afford certain benefits, under certaincircumstances. However, other embodiments may also be preferred, underthe same or other circumstances. Furthermore, the recitation of one ormore preferred embodiments does not imply that other embodiments are notuseful, and is not intended to exclude other embodiments from the scopeof the invention.

As used herein, the word “include,” and its variants, is intended to benon-limiting, such that recitation of items in a list is not to theexclusion of other like items that may also be useful in the materials,compositions, devices, and methods of this invention.

As referred to herein, all compositional percentages are by weight ofthe total composition, unless otherwise specified.

Tooth Whitening System

In various embodiments, the present invention provides an improved toothwhitening system that comprises a dental tray and a tooth whiteningcomposition. The tooth whitening composition comprises a whitening agentand a hydrophobic polymer carrier. In various embodiments of the presentinvention, the whitening composition is a viscous suspension whichmaintains its consistency during storage. The hydrophobic polymercarrier of the whitening composition is preferably not soluble in waterand is stable for longer durations during exposure to saliva and otheraqueous solutions found in an oral cavity, as compared to prior artwater-soluble whitening solutions.

Whitening Compositions

The present invention provides a whitening composition for use in atooth whitening system. In one embodiment, the whitening compositioncomprises a whitening agent and a hydrophobic polymer carrier. Thewhitening composition may further comprise an adhesion enhancing agent.Other additional ingredients that may be added include those known toone of skill in the art, including one or more of the followingcomponents: surfactants, flavoring agents, sweeteners, desensitizingagents, antimicrobial agents, anti-caries agents, anti-calculus agents,anti-inflammatory agents, vitamins, pigments and coloring agents, andenzymes, as will be discussed in greater detail below.

Active ingredients useful herein are optionally present in thecompositions of the present invention in safe and effective amounts. A“safe and effective” amount of an active is an amount that is sufficientto have the desired therapeutic or prophylactic effect in the human orlower animal subject to whom the active is administered, without undueadverse side effects (such as toxicity, irritation, or allergicresponse), commensurate with a reasonable benefit/risk ratio when usedin the manner of this invention. The specific safe and effective amountof the active will vary with such factors as the particular conditionbeing treated, the physical condition of the subject, the nature ofconcurrent therapy (if any), the specific active used, the specificdosage form, the carrier employed, and the desired dosage regimen.

Whitening Agents

In various embodiments, the compositions of the present inventioncomprise a whitening agent as the main active ingredient. As furtherdiscussed below, a “whitening agent” is a material which effectswhitening of a tooth surface to which it is applied. In variousembodiments, the whitening compositions of this invention comprise awhitening agent selected from the group consisting of peroxides,chlorites, and hypochlorites. Examples of suitable chlorites andhypochlorites include those having alkali or alkaline metal cations andinclude calcium chlorite, barium chlorite, magnesium chlorite, lithiumchlorite, sodium chlorite, potassium chlorite, calcium hypochlorite,barium hypochlorite, magnesium hypochlorite, lithium hypochlorite,lithium hypochlorite, and sodium hypochlorite.

In one embodiment, the whitening agent comprises a peroxide compound. Asreferred to herein, a “peroxide compound” is an oxidizing compoundcomprising a bivalent oxygen-oxygen group. Peroxide compounds includeperoxides and hydroperoxides, such as hydrogen peroxide, peroxides ofalkali and alkaline earth metals, organic peroxy compounds, peroxyacids, pharmaceutically-acceptable salts thereof, and mixtures thereof.Peroxides of alkali and alkaline earth metals include lithium peroxide,potassium peroxide, sodium peroxide, magnesium peroxide, calciumperoxide, barium peroxide, and mixtures thereof. Organic peroxycompounds include carbamide peroxide (also known as urea hydrogenperoxide), glyceryl hydrogen peroxide, alkyl hydrogen peroxides, dialkylperoxides, alkyl peroxy acids, peroxy esters, diacyl peroxides, benzoylperoxide, and monoperoxyphthalate, and mixtures thereof. Peroxy acidsand their salts include organic peroxy acids such as alkyl peroxy acids,and monoperoxyphthalate and mixtures thereof, as well as inorganicperoxy acid salts such as persulfate, dipersulfate, percarbonate,perphosphate, perborate and persilicate salts of alkali and alkalineearth metals such as lithium, potassium, sodium, magnesium, calcium andbarium, and mixtures thereof. In various embodiments, the peroxidecompound comprises hydrogen peroxide, urea peroxide, sodium percarbonateand mixtures thereof.

Peroxide releasing compounds particularly useful in the whiteningcompositions of the present invention include peroxide containingcompounds such as urea peroxide, sodium percarbonate, sodium perborateand polyvinylpyrrolidone-H₂0₂ complexes (hereinafter “PVP-H₂0₂”).Polyvinylpyrrolidone is also known as poly-N-vinyl-poly-2-pyrrolidoneand commonly abbreviated to “PVP”. PVP generally refers to a polymercontaining vinylpyrrolidone (also referred to as N-vinylpyrrolidone,N-vinyl-2-pyrrolidione and N-vinyl-2-pyrrolidinone) as a monomeric unit.The monomeric unit consists of a polar imide group, four non-polarmethylene groups and a non-polar methane group.

Both linear and cross-linked complexes of PVP-H₂0₂ are known in the artand are disclosed in U.S. Pat. No. 3,376,110 and U.S. Pat. No.3,480,557, which are herein incorporated by reference, and have beenused in compositions for treating acne vulgaris (U.S. Pat. No.5,122,370). PVP-H₂0₂ complexes are also disclosed in U.S. Pat. No.5,122,370. PVP-H₂0₂ is stable in an anhydrous environment. Upon exposureto highly aqueous environments, such as in the oral cavity, the PVP-H₂0₂dissociates into individual species (PVP polymer and H₂0₂). In oneembodiment, the PVP-H₂0₂ complex is about 80% by weightpolyvinylpyrrolidone and 20% by weight H₂0₂.

In alternate embodiments, the whitening agent comprises a liquidperoxide solution. The hydrophobic polymer carrier of the whiteningcomposition provides sufficient stability to permit the use of a liquidhydrogen peroxide. The liquid hydrogen peroxide comprises H₂O₂ generallycontained in an aqueous water-based solution. In some embodiments, theliquid hydrogen peroxide has a concentration of peroxide to the totalsolution of about 0.5 to about 10%, more preferably 0.5 to 5% byweight). Additionally, a stabilizer may be present. For example, a 3%hydrogen peroxide solution with about 0.1 to about 0.5% of a stabilizermay be used. Acetanilide or a similar organic material can also be usedwith a pyrophosphate stabilizer such as sodium acid pyrophosphate (about0.1 to about 1.0%) with a preferred amount of about 0.5%.

In certain embodiments, an agent to enhance release of the peroxide inthe oral cavity is present as a part of the peroxide component whiteningagent. Polypore® which is an allyl methacrylate crosspolymer availablefrom Amcol health & Beauty Solutions, Inc. is such an enhancing agent.

In various embodiments, the whitening agent of the whitening compositioncomprises from about 0.1% to about 50%, optionally from about 1% toabout 40%, and optionally from about 10% to about 30% of the oral carecomposition.

Hydrophobic Polymer Carrier

The present invention preferably comprises a carrier that comprises ahydrophobic polymer. The term “hydrophobic” or “water-insoluble” asapplied to polymers and as employed herein refers to an organic polymerwhich is substantially non-aqueous having a water solubility of lessthan one gram per 100 grams of water at 25° C. Any such polymers thatare compatible with the whitening agents previously described above, andwhich can produce a tooth whitening composition having a viscosity ofgreater than about 1,000 centipoise (cP) and less than about 900,000 cP,preferably greater than about 10,000 cP and less than about 100,000 cP,more preferably greater than 50,000 cP and less than 900,000 cP, andmost preferably from between about 200,000 cP to about 600,000 cP, arepreferred in various embodiments of the present invention.

One preferred class of hydrophobic polymers comprise siloxane polymers,which are also generally known in the art as “silicone” polymers. Incertain embodiments of the present invention, the hydrophobic polymersin the carrier are those in which a whitening agent can be dispersed andare well known in the art. Many such silicone polymers are commerciallyavailable. In various embodiments, a preferred silicone-basedhydrophobic polymer is a polyorganosiloxane. One such polyorganosiloxaneis produced by condensing a silicone resin and an organosiloxane such asa polydiorganosiloxane. Such hydrophobic polymers are an elastomeric,tacky material, adhesion of which to dental enamel surfaces can bevaried by altering the ratio of silicone resin to polydiorganosiloxanein the copolymer molecule. Preferably, the polymers are pressuresensitive hydrophobic polymers specifically designed for pharmaceuticaluse and are permeable to many drug compounds and find application forthe transdermal application of various compounds. In one suchembodiment, the silicone polymers are the copolymer product of mixing asilanol terminated polydiorganosiloxane such as polydimethyl siloxanewith a silanol-containing silicone resin whereby the silanol groups ofthe polydiorganosiloxane undergo a condensation reaction with thesilanol groups of the silicone resin so that the polydiorganosiloxane islightly crosslinked by the silicone resin (that is, thepolydiorganosiloxane chains are bonded together through the resinmolecules to give chain branching and entanglement and/or a small amountof network character) to form the silicone hydrophobic polymers. Acatalyst, for example, an alkaline material, such as ammonia, ammoniumhydroxide or ammonium carbonate, can be mixed with thesilanol-terminated polydiorganosiloxane and the silicone resin topromote this crosslinking reaction. By copolymerizing the silicone resinwith the silanol terminated polydiorganosiloxane, there results apolymer with self adhering properties and the cohesive properties of asoft elastomer matrix characteristic of pressure sensitive polymersbeing distinguished from the hard, non-elastomeric properties of othersilicone resins. In one embodiment, hydrophobic polymers used in thecarrier are available from the Dow-Corning Company under the brand nameBIO-PSA.

The modification of a ratio of silicone resin to polydiorganosiloxanemodifies the tackiness of the hydrophilic polymer. This ratio can be inthe range of about 70:30 to about 50:50. For example, the BIO PSAsilicone sold by Dow-Corning is available in three silicone resin tosilicone polymer ratios namely, 65/35 (low tack), 60/40 (medium tack),55/45 (high tack). Such a polyorganosiloxane pressure sensitive adhesiveis available dissolved in either ethyl acetate solvent or dimethicone.

In various embodiments, the hydrophobic polymer carrier is present inthe liquid whitening compositions of the present invention at aconcentration of about 1 to about 80% by weight and preferably about 15to about 40% by weight.

Adhesion Enhancing Agents

In one embodiment of the present invention, the whitening compositionfurther comprises an adhesion enhancing agent, that augments adhesion ofthe anhydrous whitening composition to the surface of the tooth, i.e.,adhesion to the enamel. Adhesion enhancing agents useful with thepresent invention include inorganic materials as well as organic naturaland synthetic polymers. Inorganic materials include amorphous silicacompounds which function as thickening agents, and include colloidalsilica compounds available under trademarks such as Cab-o-sil fumedsilica manufactured by Cabot Corporation and distributed by LenapeChemical, bound Brook, N.J.; Zeodent 165 from J.M. Huber ChemicalsDivision, Havre de Grace, Md. 21078; and Sylox 15 also known as Sylodent15, available from Davison Chemical Division of W.R. Grace Corporation,Baltimore, Md. 21203. In certain embodiments, the inorganic adhesionenhancing material, such as silica, is surface treated to compatibilizethe adhesion enhancing agent with the hydrophobic components in thewhitening system.

Organic materials which may be included in the compositions of thepresent invention to enhance the properties of the hydrophobic polymersof the present invention include adhesion enhancing agents such aswaxes, inclusive of bees' wax, mineral oil, plastigel, (a blend ofmineral oil and polyethylene), petrolatum, white petrolatum, shellac,versagel (blend of liquid paraffin, butene/ethylene/styrene hydrogenatedcopolymer) polyethylene waxes, microcrystalline waxes, polyisobutene,polyvinyl pyrrolidone/vinyl acetate copolymers, and insolublepolyacrylate copolymers.

Also effective as adhesion enhancing agents are liquid hydrophilicpolymers including polyethylene glycols, nonionic polymers of ethyleneoxide having the general formula:HOCH₂(CH₂OCH₂)_(n)CH₂OHwherein n represents the average number of oxyethylene groups.Polyethylene glycols available from Dow Chemical are designated by anumber such as 200, 300, 400, 600, 2000 which represents the approximateaverage molecular weight of the polymer, as well as nonionic blockcopolymer of ethylene oxide and propylene oxide of the formula:HO(CH₄O)_(a)(C₃H₆O)_(b)(C₂H₄O)_(c)HThe block copolymer is preferably chosen (with respect to a, b and c)such that the ethylene oxide constituent comprises from about 65 toabout 75% by weight, of the copolymer molecule and the copolymer has anaverage molecular weight of from about 2,000 to about 15,000 with thecopolymer being present in the liquid tooth whitening composition insuch concentration that the composition is liquid at room temperatures(23° C.).

A particularly desirable block copolymer for use in the practice of thepresent invention is available commercially from BASF and designatedPluraflo L1220 which has an average molecular weight of about 9,800. Thehydrophilic poly(ethylene oxide) block averages about 65% by weight ofthe polymer.

Adhesion enhancing agents employed in compositions of variousembodiments of the invention are present in an amount of from about 0 toabout 20% by weight. Preferably, the adhesion enhancing agents arepresent in an amount of from about 2 to about 15% by weight.

Additional Ingredients

As previously described, many other components may further be includedin the whitening compositions of the present invention, and includeflavors, sweetening agents, surfactants, anti-microbial agents,anti-inflammatory agents, plaque buffers, vitamins, anti-caries agents,anti-plaque agents, desensitizing agents, coloring agents, pigments andopacifying agents, for example.

In certain embodiments, nonionic surfactants are present in thewhitening composition. These surfactants are preferably compatible withthe whitening agents and serve as solubilizing, dispersing, emulsifyingand wetting agents. In one aspect, surfactants are especially effectiveto solubilize a flavoring agent, if flavor is desired for the liquidwhitening composition. A particularly useful nonionic surfactant is awater soluble polyoxyethylene monoester of sorbitol with a C10 to C18fatty acid, marketed commercial under the Tween trademark. The Tweensurfactants are mixtures of C10 to C18 fatty acid esters of sorbitol(and sorbitol anhydrides), consisting predominately of the monoester,condensed with about 10-30, preferably about 20, moles of ethyleneoxide.The fatty acid (aliphatic hydrocarbonyl monocarboxylic acid) may besaturated or unsaturated, e.g., lauric, palmitic, stearic, oleic acids.Polysorbate 20 (e.g., Tween 20) is especially preferred and is commonlyreferred to as polyoxyethylene (20) sorbitan monolaurate. The nonionicsurfactant constitutes about 0 to 50% by weight and preferably 0.5 to40% by weight of the liquid composition.

In an embodiment where the whitening composition has a flavoring agent,the flavoring agent is selected from essential oils, as well as variousflavoring aldehydes, esters, alcohols, and similar materials. Examplesof the essential oils include oils of spearmint, peppermint,wintergreen, sassafras, clove, sage, eucalyptus, marjoram, cinnamon,lemon, lime, grapefruit, and orange. Also useful are such chemicals asmenthol, carvone, and anethole. Of these, the most commonly employed arethe oils of peppermint, spearmint and wintergreen. The flavoring agentis preferably incorporated in the whitening composition of the presentembodiment at a concentration of about 0 to about 2% by weight and morepreferably about 0.1 to about 0.5% by weight.

In embodiments where the whitening composition is sweetened, asweetening material is used as an alternative or complement to theflavoring agent. Suitable sweetening agents are water-soluble andinclude sodium saccharin, sodium cyclamate, xylitol, perillartien,D-tryptophan, aspartame, dihydrochalcones and the like, inconcentrations of about 0.01 to about 1% by weight. Sodium saccharin ispreferred.

Other ingredients which are included in various embodiments of theliquid whitening composition comprise materials commonly used in theoral care formulations. These include: antimicrobial agents, e.g.,Triclosan, chlorhexidine, copper-, zinc- and stannous salts such as zinccitrate, zinc sulphate, zinc glycinate, sodium zinc citrate and stannouspyrophosphate, sanguinarine extract, metronidazole, quaternary ammoniumcompounds, such as cetylpyridinium chloride; bis-guanides, such aschlorhexidine digluconate, hexetidine, octenidine, alexidine; andhalogenated bisphenolic compounds, such as 2,2′methylenebis-(4-chloro-6-bromophenol); antiinflammatory agents such asibuprofen, flurbiprofen, aspirin, indomethacine; anticaries agents suchas sodium-, calcium-, magnesium- and stannous fluoride, aminefluorides,disodium monofluorophosphate and sodium trimetaphosphate; plaque bufferssuch as urea, calcium lactate, calcium glycerophosphate and strontiumpolyacrylates; vitamins such as Vitamin C; plant extracts; desensitizingagents, e.g., potassium citrate, potassium chloride, potassium tartrate,potassium bicarbonate, potassium oxalate, potassium nitrate andstrontium salts; agents effective against dental calculus such aspyrophosphate salts including the mono, di, tri and tetra alkali metaland ammonium pyrophosphate and tripolyphosphate salts; biomolecules,e.g., bacteriocins, antibodies, enzymes such as papain, glucoamylase;opacifying agents, pigments, coloring agents and fluoride ion providingsalts having anticaries efficacy such as sodium fluoride, potassiumfluoride, a tin fluoride such as stannous fluoride.

In one embodiment, the tooth whitening composition has the followinggeneral formula:

Component Content Hydrophobic Polymer Carrier 1 to 80 wt % AdhesiveEnhancing Agent 0 to 20 wt % Whitening Agent (Peroxide) 0.5 to 50 wt %Surfactant 0 to 50 wt % Flavor 0.1 to 1 wt % Other Components (can beHOH) 0 to 10 wt %

Dental Trays

In various embodiments of the present invention, the teeth whiteningsystem comprises a dental tray operable to conform to the surface of atooth or plurality of teeth. The tooth whitening composition can beapplied to the surface of the dental tray by manual application, such asby painting. Thus, the dental tray is operable to retain whiteningcomposition and to be inserted into the oral cavity. Further, the dentaltray preferably has one or more surfaces that are operable to confrontat least one surface of a tooth that is to be whitened.

Dental trays are well-known in the art. A dental tray can be generic(e.g., off-the-shelf) or custom designed for the subject (human or otheranimal) with which it is to be used. In either type of dental tray, asurface of the tray is contacted with the tooth (usually with multipleteeth), and the whitening composition is permitted to bathe or coat thetooth/teeth. The dental tray will fit within a subject's mouth, and maycover all of the upper or lower teeth or a portion thereof. In certainembodiments, one dental tray may fit over both the upper and lowerteeth, such as a mouth guard typically worn by athletes. The dental traycomprises a tooth bed or reservoir formed between an inner and an outersidewall. The teeth are placed into the tooth bed. The outer sidewallwill accordingly be disposed between the outer surface of the teeth anda patient's cheeks, and the inner sidewall will be disposed between theinner surface of the patient's teeth and the mouth cavity. Dental traysdesigned to simultaneously fit over the upper and lower teeth preferablyinclude air passages to permit the wearer of the dental tray to breathe.

The dental tray can be of any conventional form and made fromconventionally used thermoplastic polymers. Thermoset polymers also canbe used. Consequently, the tray can range from highly flexible to a lowflexibility. The thermoplastic polymers useful in various embodiments ofthe present invention include polyethylene and polypropylene polymerstheir derivatives and copolymers, silicone elastomers, polyurethanes andderivatives, polycaprolactams, polystyrene and derivatives,polybutadiene and derivatives, polyisoprene and derivatives, andpolymethacrylate and its derivatives. These can be in a sheet, foam or alaminate form. In forming a customized dental tray, a cast is taken ofthe teeth and gum area of a patient and set. A thermoplastic polymerfilm is placed over the cast and vacuum formed to the shape of the teethand gum margin of the patient. In this manner, a tray in the shape ofthe teeth having a reservoir or bed that can contain a whiteningformulation is formed, and can thus be used to treat the patient'steeth.

In one embodiment, the whitening composition is applied by the end-user(a consumer or dental care professional) to the surfaces of the dentaltray prior to use, such that the whitening composition contacts thesurfaces of the teeth to be whitened. In an alternate embodiment, thewhitening composition may be applied to the dental tray and shipped tothe end-user with the whitening composition contained in a storagereservoir.

Tooth Whitening Kit

In an embodiment according to the present invention, a tooth whiteningkit is provided, for whitening the surface of a tooth in the oral cavityof a human or other animal subject, comprising a dental tray operablefor insertion into the oral cavity of the subject comprising areservoir. Such a dental tray may be selected to correspond to any ofthe embodiments described above or of those known to one of skill in theart. The tooth whitening kit further comprises a tooth whiteningcomposition comprising a peroxide whitening agent and a hydrophobicsiloxane polymer carrier having a viscosity of at least about 50,000centipoise. In one embodiment, the tooth whitening kit may be employedto the surface of a tooth in the oral cavity of a human or other animalsubject using the kit described above, where the whitening compositionis applied to the reservoir in the dental tray of the kit and the trayis then inserted into the oral cavity so that the whitening compositionis contacted with the surface of the tooth.

Methods

In one embodiment, the present invention provides a method of whiteningthe surface of a tooth in the oral cavity of a human or other animalsubject using a tooth whitening system comprising a dental tray having asurface operable to confront a tooth surface, and a tooth whiteningcomposition comprising a whitening agent and a hydrophobic polymercarrier. The method comprises applying the composition to the dentaltray and inserting the tray into the oral cavity so that the compositionis contacted with the surface of the tooth. The contacting occurs for aduration of time sufficient to satisfactorily effect whitening of theteeth. Thus, the contacting occurs for a sufficient period of time to atleast partially whiten teeth. This can be a period of time from about0.5 hour to 2 hours or longer. The substantially non-aqueous toothwhitening composition is effective over a longer period of time, sinceit is not significantly diluted or removed from the dental tray duringthe treatment time.

In another embodiment, a method of whitening a surface of a tooth isprovided comprising contacting the surface with a whitening compositioncontained in a dental tray, where the whitening composition comprises awhitening agent and a hydrophobic polymer carrier. In certainembodiments, before the contacting, a dental tray is formed thatsubstantially conforms to a surface of a tooth, or a plurality of teeth,to be whitened. Further, after the contacting, the method comprisesremoving the dental tray from the surface of the tooth and then treatingthe surface of the tooth with a desensitizing composition in certainembodiments. The tooth desensitizing formulation can be applied via useof the dental tray. In alternate embodiments, the desensitizingcomposition is applied via use of a desensitizing toothpaste for severaldays after the whitening procedure. Such desensitizing formulationspreferably contain at least one of the following: potassium nitrate,citric acid, citric acid salts, strontium chloride and the like. Aprocess where the tooth whitening procedure is followed by a toothdesensitizing procedure is preferred for subjects who are susceptible totooth sensitivity problems.

The liquid whitening compositions of the present invention are preparedby adding and mixing the ingredients of the composition in a suitablevessel such as a stainless steel tank provided with a mixer. In thepreparation of the liquid whitening composition, the ingredients areadvantageously added to the mixer in the following order: liquidanhydrous silicone based pressure sensitive polymer (hydrophobic polymercarrier), peroxide whitening agent, adhesion enhancing agent and anydesired flavoring or sweetener. The ingredients are then mixed to form ahomogeneous dispersion/solution. The moisture content of the toothwhitening composition will be about 0.05% by weight to about 10% byweight, and preferably about 2% by weight to about 8% by weight. Theviscosity of such a composition is about 50,000 centipoise to about900,000 centipoise and preferably about 200,000 centipoise to about600,000 centipoise.

EXAMPLES

The present invention is illustrated by the following examples but isnot to be limited thereby.

Examples 1-4

The formulations in the following Table 1 are formed by adding siliconehydrophobic polymers commercially available as Dow Corning Q7-9120 andDow Corning 8-7016 in a dimethicone solvent to a Brogli mixer. These twocomponents are mixed for 30 minutes at high speed without vacuum. Sodiumsaccharin is added and mixed continuously for 3 minutes at high speedwithout vacuum. A COP Plastigel 5 is then added and mixed continued for10 minutes at high speed without vacuum. The Polyplasdoxyl XL10, 35%hydrogen peroxide peralkali and flavor are added and mixed on low speedwithout vacuum for 5 minutes. Full vacuum is then applied and theformulation is mixed at high speed for an additional 15 minutes.

TABLE 1 Example 1 Example 2 Example 3 Example 4 Ingredient (Wt. %) (Wt.%) (Wt. %) (Wt. %) Dow Corning 30.0 30.0 30.0 30.0 8 - 7016 Dow Corning20.0 16.46 — 20.0 Q7 - 9120 Pluracare — — — 0.05 L 1220 Polyplasdone25.0 25.0 25.0 25.0 XL-10 COP 20.1 15.5 11.91 Plastigel 5 (Lyne Labs)35% 4.0 12.14 44.1 12.14 Hydrogen Peroxide Peralkali Sodium 0.3 0.3 0.300.30 Saccharin VW Mint 0.6 0.6 0.6 0.60 Flavor Viscosity 180,000 180,000270,000 360,000 centipoises (cP)

The formulations of Examples 1-4 have viscosities of about 180,000 cP to360,000 cP. These formulations will have a workable consistency whenbeing applied to a tray and in adherence to teeth. There also is a lowloss of the composition from the tray by the natural flushing action ofsaliva.

What is claimed is:
 1. A tooth whitening system comprising: a dentaltray having a surface operable to confront a tooth surface; and a toothwhitening composition having an overall viscosity of greater than 50,000centipoise and less than 900,000 centipoise, comprising: between 0.5 toabout 50 weight % of a whitening agent selected from the groupconsisting of peroxides, chlorites and hypochlorites; between 1 to about80 weight % of a pressure-sensitive, hydrophobic polymer carriercomprising silicon resin and polydiorganosiloxane; between 0.1 to 1weight % of a flavoring agent; and between 2 to 15 weight % of anadhesion enhancing agent consisting of polyethylene gelled mineral oilthat augments adhesion of said tooth whitening composition to toothsurfaces.
 2. A system according to claim 1, wherein said whiteningcomposition has a viscosity of between about 200,000 centipoise to about600,000 centipoise.
 3. A system according to claim 1, wherein saiddental tray is a material selected from the group consisting of: athermoplastic resin and a thermoset resin.
 4. A system according toclaim 1, wherein the tooth whitening composition is contained in thedental tray.
 5. A tooth whitening system consisting of: a dental trayhaving a surface operable to confront a tooth surface; and a toothwhitening composition having a viscosity of greater than 50,000centipoise and less than 900,000 centipoise comprising: a whiteningagent selected from the group consisting of peroxides, chlorites andhypochlorites; a hydrophobic polymer carrier, and an adhesion enhancingagent consisting of polyethylene gelled mineral oil that augmentsadhesion of said tooth whitening composition to tooth surfaces.